Recognition of climatic drought in the Anzali wetland basin on the southwestern coast of the Caspian Sea

摘要

Anzali wetland is an internationally important wetland that was recorded as a Ramsar site in June 1975. With an area of 19.3 km2, this wetland is located on the southwestern coast of the Caspian Sea in Guilan Province, Iran It affects bird life, aquatics, social-economic conditions of margin settlements, wetland plants, and the surrounding climate and hydrology. Drought is a phenomenon that is an anomaly in the system and to recognise this phenomenon statistically the Normal Percent Precipitation Index (NPPI) and Standard Precipitation Index (SPI) were used for the period from 1980 to 2005, As NPPI does not distinguish drought so well, the SPI index with a moving average control chart and the Gamble method with geographical information system (GIS) software were used The research results showed that the wetland experienced drought during this time period and the mountainous zones had a wet period.